Green Tea Extract

Effects and Benefits

Core Identification

Common Names:
- Green Tea Extract
- Green Tea
- Matcha (powdered form)
- Chinese Tea
- Japanese Tea

Latin Name: Camellia sinensis

Category: Herb

Uses

Traditional Uses

• Mental alertness and energy - Traditional Chinese and Japanese medicine, 2,000+ years
• Digestive support - Traditional Asian medicine
• General wellness tonic - Used across Asian cultures since approximately 2737 BC

Modern Uses

• Weight Management/Thermogenesis - Increases energy expenditure and fat oxidation | Research quality: Moderate
• Key findings: Clinical trials showed 4% increase in 24-hour energy expenditure and significant increase in fat oxidation compared to placebo; effects exceed those of equivalent caffeine alone. One trial with green tea phytosome showed 30 lbs weight loss over 90 days vs. 10 lbs in control group.

• Source citations: Barrett, Handbook of Clinically Tested Herbal Remedies; Dulloo et al., American Journal of Clinical Nutrition (1999); Colbert, Reversing Diabetes

• Antioxidant Activity - Increases plasma antioxidant capacity and protects LDL from oxidation | Research quality: Moderate

• Key findings: Single doses of green tea significantly increased plasma antioxidant activity within 60 minutes; antioxidants appear 100 times more powerful than vitamin C and 25 times more powerful than vitamin E.

• Source citations: Leenen et al., European Journal of Clinical Nutrition (2000); Brewer, Encyclopedia of Vitamins

• Cardiovascular Support - May support healthy cholesterol levels and blood vessel function | Research quality: Moderate

• Key findings: Meta-analysis showed green tea may lower LDL by 1-5 points; catechins help break down cholesterol and increase elimination; prevents blood from "clumping together."

• Source citations: Peters et al., American Journal of Epidemiology (2001); Mars, Home Reference to Holistic Health

• Cognitive Function - Supports mental alertness and may have neuroprotective properties | Research quality: Preliminary

• Key findings: Contains L-theanine which promotes relaxation while maintaining alertness; catechins may protect nerve cells from oxidative damage characteristic of neurodegenerative conditions.

• Source citations: Mars, Home Reference to Holistic Health; Stewart, Living the Good Long Life

• Blood Sugar Support - May help moderate blood sugar levels | Research quality: Preliminary

• Key findings: Slows sugar release from starchy foods; helps keep blood sugar levels moderate.
• Source citations: Balch, Prescription for Herbal Healing; Mars, Home Reference to Holistic Health

Active Compounds

Primary Active Ingredients:
- EGCG (Epigallocatechin gallate) - The most potent catechin; primary antioxidant responsible for most health benefits; inhibits certain enzymes and promotes thermogenesis
- Catechins - Flavonoid polyphenols comprising 30%+ of dry leaf weight; powerful antioxidants that protect cells from oxidative damage
- Caffeine - Stimulant (25-50mg per cup); works synergistically with EGCG to enhance thermogenic effects
- L-theanine - Amino acid that promotes relaxation and increases GABA, serotonin, and dopamine; offsets stimulatory effects of caffeine
- Theophylline and Theobromine - Additional methylxanthines contributing to stimulant effects

Dosage Information

Standard Dosage:
- Form: Standardized extract capsule
- Amount: 250-500mg extract daily (standardized to 50-97% polyphenols)
- Frequency: Once or twice daily with food

Therapeutic Dosage:
- Form: Standardized extract or tea
- Amount: 270-375mg catechins (including 90mg+ EGCG) three times daily; or 3-5 cups brewed tea daily
- Purpose: Weight management, antioxidant support
- Duration: 4-12 weeks for weight management studies; ongoing for general health

Maximum Safe Dosage:
- Daily maximum: 800mg EGCG from supplements; concentrated extracts linked to liver concerns at very high doses
- Warning threshold: Avoid highly concentrated extracts exceeding recommended doses; liver injury reported with some weight-loss products containing concentrated green tea

Bioavailability Notes:
- Green tea phytosome (combined with phospholipids) shows significantly enhanced absorption of polyphenols
- Addition of milk does not appear to reduce antioxidant absorption
- Taking with food may reduce stomach upset but slightly reduce absorption

How to Take It

Timing:
- Morning or early afternoon preferred (due to caffeine content)
- With food to minimize potential stomach upset
- Avoid within 4-6 hours of bedtime to prevent sleep interference
- Do not take within 1 hour of other medications to avoid dilution effects

Synergies - What It Works Well With

Complementary Supplements:
1. Vitamin C - Both are antioxidants; may enhance overall antioxidant protection
2. Fish Oil - Complementary cardiovascular support through different mechanisms
3. Quercetin - Another polyphenol that may enhance anti-inflammatory effects

Avoidance - What NOT to Combine With

Supplement Interactions:
1. Iron supplements - Green tea tannins can reduce iron absorption; take separately by 2+ hours
2. Stimulants (caffeine, guarana, ephedra) - Additive stimulant effects may cause nervousness, rapid heartbeat

Drug Interactions:
1. Anticoagulants (Warfarin/Coumadin) - Green tea contains vitamin K which can reduce drug effectiveness | Severity: Moderate to Severe
2. MAO Inhibitors - Caffeine content may cause dangerous interaction | Severity: Severe
3. Stimulant medications - Additive effects on heart rate and blood pressure | Severity: Moderate
4. Adenosine - Caffeine blocks adenosine effects | Severity: Moderate
5. Lithium - May affect lithium clearance | Severity: Moderate
6. Beta-blockers (Nadolol) - Caffeine may reduce effectiveness | Severity: Mild

Food Interactions:
- Iron-rich foods - Take separately to maximize iron absorption
- Other caffeinated beverages - Combined caffeine intake may cause overstimulation

Safety Information

Contraindications:
- Caffeine sensitivity or caffeine-related conditions
- Liver disease or history of liver problems
- Bleeding disorders (due to antiplatelet effects)
- Anxiety disorders (caffeine may exacerbate)
- Heart arrhythmias
- Hyperthyroidism

Side Effects:
- Common: Stomach upset, reduced appetite, nervousness, insomnia (especially at higher doses)
- Rare: Liver injury with concentrated extracts; constipation; headache
- Note: Infants may develop anemia from excessive intake

Long-Term Use:
- Tea consumption has been safely used for thousands of years
- Concentrated extracts: Use caution with prolonged high-dose supplementation
- Monitor liver function if using high-dose extracts long-term
- Consider cycling: 8-12 weeks on, 2-4 weeks off for concentrated extracts

Special Precautions:
- Pregnancy: Avoid or limit due to caffeine content (10-50mg per cup depending on preparation)
- Nursing: Caffeine passes into breast milk and may affect infant sleep
- Surgery: Discontinue 2 weeks before surgery due to potential effects on blood clotting and blood pressure
- Children: Not recommended for young children; may cause anemia
- Iron deficiency: May worsen; separate from iron-containing foods/supplements

Primary Uses At-a-Glance

Primary: Antioxidant support, Weight management, Cardiovascular health, Mental alertness

Secondary: Blood sugar support, Oral health, Skin protection, Exercise performance

Sources

Local Library:
- Barrett, Marilyn - The Handbook of Clinically Tested Herbal Remedies Vol 1 & 2
- Balch, Phyllis - Prescription for Herbal Healing
- Brewer, Sarah - TDT Encyclopedia of Vitamins
- Colbert, Don - Reversing Diabetes
- Mars, Brigitte - The Home Reference to Holistic Health and Healing
- Moyad, Mark - The Supplement Handbook
- Weil, Andrew - Eating Well for Optimum Health
- White, Linda B. - 500 Time-Tested Home Remedies
- Buhner, Stephen Harrod - Herbal Antibiotics
- Grogan, Barbara Brownell - Healing Herbs Handbook

General Knowledge:
- Dulloo AG et al. (1999). American Journal of Clinical Nutrition 70(6):1040-1045
- Leenen R et al. (2000). European Journal of Clinical Nutrition 54(1):87-92
- Peters U et al. (2001). American Journal of Epidemiology 154(6):495-503